将图像从 mysql 数据库加载到图片框时出错。空引用异常
Error loading image to picturebox from mysql database. NullReferenceException
我正在尝试从数据库中获取图像并显示到图片框中。我的代码在下面
private void getImage()
{
using (MySqlConnection conn = new MySqlConnection(connectionManager.connectionString))
{
try
{
conn.Open();
string query = "SELECT 'Image' FROM student_img WHERE ID = @ID";
MySqlCommand cmd = new MySqlCommand(query, conn);
int id = 10;
cmd.Parameters.AddWithValue("@ID", id);
var da = new MySqlDataAdapter(cmd);
var ds = new DataSet();
da.Fill(ds, "Image");
int count = ds.Tables["Images"].Rows.Count;
if (count > 0)
{
var data = (Byte[])(ds.Tables["Images"].Rows[count - 1]["Image"]);
var stream = new MemoryStream(data);
picLogo.Image = Image.FromStream(stream);
}
}
catch (Exception ex)
{
MessageBox.Show("Connection Error!\n" + ex.Message, "Error Message",
MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
}
但是我收到 NullReferenceException 错误。我还有另一种方法,也许我可以以某种方式使用它,但我不确定如何从数据库中获取数据,因为我是 C#
的新手
public Image byteArrayToImage(byte[] byteArrayIn)
{
MemoryStream ms = new MemoryStream(byteArrayIn);
Image returnImage = Image.FromStream(ms);
return returnImage;
}
设法解决了问题,不得不更改
Images
到
Image
private void getImage()
{
using (MySqlConnection conn = new MySqlConnection(connectionManager.connectionString))
{
try
{
conn.Open();
string query = "SELECT Image FROM student_img WHERE ID = @ID";
MySqlCommand cmd = new MySqlCommand(query, conn);
int id = 10;
cmd.Parameters.AddWithValue("@ID", id);
var da = new MySqlDataAdapter(cmd);
var ds = new DataSet();
da.Fill(ds, "Image");
int count = ds.Tables["Image"].Rows.Count;
if (count > 0)
{
var data = (Byte[])(ds.Tables["Image"].Rows[count - 1]["Image"]);
var stream = new MemoryStream(data);
picLogo.Image = Image.FromStream(stream);
}
}
catch (Exception ex)
{
MessageBox.Show("Connection Error!\n" + ex.Message, "Error Message",
MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
}
我正在尝试从数据库中获取图像并显示到图片框中。我的代码在下面
private void getImage()
{
using (MySqlConnection conn = new MySqlConnection(connectionManager.connectionString))
{
try
{
conn.Open();
string query = "SELECT 'Image' FROM student_img WHERE ID = @ID";
MySqlCommand cmd = new MySqlCommand(query, conn);
int id = 10;
cmd.Parameters.AddWithValue("@ID", id);
var da = new MySqlDataAdapter(cmd);
var ds = new DataSet();
da.Fill(ds, "Image");
int count = ds.Tables["Images"].Rows.Count;
if (count > 0)
{
var data = (Byte[])(ds.Tables["Images"].Rows[count - 1]["Image"]);
var stream = new MemoryStream(data);
picLogo.Image = Image.FromStream(stream);
}
}
catch (Exception ex)
{
MessageBox.Show("Connection Error!\n" + ex.Message, "Error Message",
MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
}
但是我收到 NullReferenceException 错误。我还有另一种方法,也许我可以以某种方式使用它,但我不确定如何从数据库中获取数据,因为我是 C#
的新手public Image byteArrayToImage(byte[] byteArrayIn)
{
MemoryStream ms = new MemoryStream(byteArrayIn);
Image returnImage = Image.FromStream(ms);
return returnImage;
}
设法解决了问题,不得不更改
Images
到
Image
private void getImage()
{
using (MySqlConnection conn = new MySqlConnection(connectionManager.connectionString))
{
try
{
conn.Open();
string query = "SELECT Image FROM student_img WHERE ID = @ID";
MySqlCommand cmd = new MySqlCommand(query, conn);
int id = 10;
cmd.Parameters.AddWithValue("@ID", id);
var da = new MySqlDataAdapter(cmd);
var ds = new DataSet();
da.Fill(ds, "Image");
int count = ds.Tables["Image"].Rows.Count;
if (count > 0)
{
var data = (Byte[])(ds.Tables["Image"].Rows[count - 1]["Image"]);
var stream = new MemoryStream(data);
picLogo.Image = Image.FromStream(stream);
}
}
catch (Exception ex)
{
MessageBox.Show("Connection Error!\n" + ex.Message, "Error Message",
MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
}